A Data Visualization of the Interprovincial Pipeline Oil Spill History

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Based on the article: Kheraj, Sean. “A History of Oil Spills on Long-Distance Pipelines in Canada.” The Canadian historical review 101, no. 2 (2020): 161–191.

Onshore oil pipeline spills and leaks have been a regular occurrence in Canada ever since corporations began to lay these long-distance steel veins in the mid-twentieth century. The Interprovincial Pipeline is no exception to this rule, as the incident report of the National Energy Board (NEB) shows.[1] 

That document, retrieved from Library and Archives Canada in Ottawa, reveals partial answers to such questions as; what were the causes of Interprovincial’s recorded spills; how much oil has the line spilled over the years; and where have they occurred most?

This article offers some initial visualizations (graphs and diagrams) of the NEB dataset to help answer these questions. The dataset itself is attached as well. This page thereby hopes to function as a point of departure for anyone interested in the history of Canada’s oil pipeline spills. The visualizations help illustrate that spills on the Interprovincial Pipeline did not conform to an obvious pattern over time. Instead, its spills occurred most often in an unpredictable fashion, making it tough to formulate an effective policy response

The Line and its Spills

The Interprovincial pipeline today consists of multiple segments in Canada and the United States that span thousands of kilometres from Edmonton in the west to Montreal in the east, crossing through the provinces of Alberta, Saskatchewan, Manitoba, Ontario, and Quebec and the U.S. states of North Dakota, Minnesota, Wisconsin, Illinois, Indiana, Michigan, and New York. Build in 1949, it has leaked oil, in every Canadian province it traversed, since its very start, as the following map reveals. 

The earliest spills remained largely unrecorded, but the National Energy Board has documented any that have occurred since 1961. The NEB also recorded what brought them about. 


The NEB identifies the causes of most spills, albeit in a rather general fashion. “Hardware Failure” was listed most frequently as the cause of oil spills, forty-nine times. The details that operators added over the years to this type of failure reveal that they could range from cracks in valves to failures of seals, and metal fatigue. The second most common cause of spills was “miscellaneous,” “unknown,” “unknown by company” or unavailable causes (represented in the figure as “N/A”). Forty-three out of one-hundred-eighty-nine reports of these were made. That is nearly twenty-three percent. Both “Earth Movement” and “Weld Corrosion” caused the least number of spills. “Earth Movement” referred to frost heave inflicted damage. “Weld Corrosion,” according to the NEB incident report, meant, “two pinhole leaks on a welding bar.”   

In hindside, after cross-referencing the NEB report with other material, some oil spills could perhaps have been prevented. Prior to the line’s opening in 1950, the company did not conduct hydrostatic pressure testing.[2] Instead, the Board of Transport Commissioners allowed Interprovincial to skip the tests with water and test the line with oil instead.[3] This resulted in at least two oil spills between Edmonton and Superior. After the opening of the line, farmers along the right of way discovered a variety of other spills and leaks. The Globe and Mail reported that in November 1950, Interprovincial spilled roughly litres of crude oil in a farmer’s field in Minnesota. Another major leak occurred a couple of months later in early 1951 when a contractor working in North Dakota accidentally struck the line with his equipment. 

 Spill Frequency and Quantity

However, oil spills remained unpredictable. The following diagram illustrates that the problem of oil spills became especially acute in the 1970s, at the height of Interprovincial’s expansion. Between 1973 and 1975, the company experi­enced what one newspaper report described as “an unusually high spill rate.” According to the NEB’s incident data, the company reported twenty-four oil spills, totaling nearly eleven million litres spilled into the environment between 1973 and 1975. The high rate of oil spills and the catastrophic volumes caught the attention of both federal and provincial authorities. Alberta’s environment minister, Bill Yurko, was especially disturbed by a couple of major spills near Strome, Alberta, in January 1974, which resulted in more than five million litres of crude oil being spilled. 

David Flemming, Operations manager for Interpro­vincial in the 1970s, described the experience of discovering oil spills in this period as follows: 

“It’s always about three in the morning when you get a call that you have a leak. The computers in the control room pick up a loss in pressure someplace, and they know it’s between here and there that there’s a leak. They can’t say it’s right at milepost so-and-so plus so many feet. And they immediately shut down the line. Then they notify the manager of operations, the district supervisor or the western division manager.”

David Flemming, Operations Manager Interprovincial

The most environmentally disastrous oil spills in the history of the Interprovincial system tended to be influenced by volume, location, and product type, and they tended to be caused by faulty welds, other construction defects, and human error. For instance, the 1974 spill, near Strome, Alberta, was caused by a five-foot-long split along a faulty longitudinal weld that released 4,452,000 litres of crude oil, flooding an estimated 30,000-square-foot area. Even more dangerous conditions were evident just a couple of years later in 1976 outside of Killam, Alberta, where a faulty weld leaked 2,385,000 litres of oil across 5.6 acres of land. During the clean-up operations, the oil ignited, injuring seven employees and killing two. Again, fire continued to be a hazard on the Interprovincial pipeline when, in February 1985, approximately 2,800,000 litres of liquid natural gas escaped from a crack in a repair sleeve weld on an original portion of the line near Camrose, Alberta. A nearby vehicle engine ignited vapours from the spill, killing two men, injuring three others, and burning more than a hectare of land.

Between 1962 to 1996, the year 1967 was Interprovincial’s worst. In that year, the company delivered approximately thirty-seven billion litres of liquid hydrocarbons and they spilled 11,081,500 litres of oil. In total over the course of its history from 1962 to 1987, Interprovincial lost 0.003 percent of the total volume of liquid hydrocarbon deliveries. Despite all the oil spilled, it was thus still more than ninety-nine percent successful. The small fraction of spills, however, in reality, meant that more than forty-one million litres spilled. Between 1962 and 1996, Interprovincial reported a total of one-hundred-ninety oil spills. This meant that Interprovincial’s annual spill rate during this period was 5.43 spills a year. 

 Spill Locations

These litres of oils were mostly spilled in rural communities made up of both settler farmers and Indigenous people. Urban areas were rarely subjected to oil spills as onshore spills occurred mostly in rural areas along the right-of-way or at isolated tank farms and pump stations. Most spills occurred at pump stations and other facilities (sixty-seven percent), but spills on the main line tended to release more liquid hydrocarbons, with seventy-seven percent of the total spill volume from 1962 to 1996 leaked from incidents on the main line of the Interprovincial. Those living along the routes of Interprovincial in so-called “landscapes of intensification” held limited power to challenge large, foreign-owned pipeline corporations. Without effective means of resistance, Interprovincial could continue to accept a minimum threshold of failures.

 On the NEB Incident Report

Since 1961, the NEB has required Interprovincial to provide reports on a range of incident types, including oil spills. The NEB keeps these reports in a large database that also contains occurrences that are not spills and incidents on other pipelines. 

The information in this article largely comes from the NEB’s incident report, which covers the period 1961 to 1996. The incident report has its flaws. For starters, any incidents that occurred prior to 1961 remain unrecorded. Alternative records like newspaper sources or public accounts offer some insight into these but conducting a systematic analysis at a level that is comparable to the cases post-1961 is impossible. Secondly, many small incidents, likely, went unreported. For the post-1961 period, the information available is wide-ranging. Thirty-four fields make up the incident report, ranging from “type of incident,” to “causes,” and “quantity of product spilled.” The report also contains a field labelled, “other.” This category contains valuable insights for more qualitative analysis. The information is helpful but leaves much to be desired. The main flaw of the incident report is thereby missing information. 

An excel version of the Interprovincial Pipeline’s part of the incident report can be found below.

Construction of the Interprovincial Pipeline. Retrieved from, “Concentrated Gravity Work in Ontario,” Financial Post, Nov. 24, 1951, P.50.

[1] The National Energy Board (NEB) is the Canadian regulatory body that oversees energy infrastructure that crosses interprovincial and national boundaries. 

[2] A hydrostatic test is a test of a pipeline with water. In a hydrostatic test, there is residual oil in the line. When there is a spill during a hydrostatic test, the residual oil spills along with the water. 

[3] “The Board assumed jurisdiction over express, telephone and telegraph tolls, railway safety, electric power rates, approval of tolls for international bridges and tunnels, and jurisdiction over the abandonment of rail lines.” “Board of Transport Commissioners,” Courthouse Libraries, July 6, 2022, https://www.courthouselibrary.ca/how-we-can-help/our-legal-knowledge-base/board-transport-commissioners